Add comments when subclassing Any (#9732)

stubs/Pillow/PIL/ImageQt.pyi

@@ -3,7 +3,10 @@ from typing_extensions import Literal, TypeAlias
 
 from .Image import Image
 
-_QImage: TypeAlias = Any  # imported from either of {PyQt6,PySide6,PyQt5,PySide2}.QtGui
+# imported from either of {PyQt6,PySide6,PyQt5,PySide2}.QtGui
+# These are way too complex, with 4 different possible sources (2 deprecated)
+# And we don't want to force the user to install PyQt or Pyside when they may not even use it.
+_QImage: TypeAlias = Any
 _QPixmap: TypeAlias = Any
 
 qt_versions: Any

stubs/mock/mock/mock.pyi

@@ -81,6 +81,8 @@ class _CallList(list[_Call]):
 class Base:
     def __init__(self, *args: Any, **kwargs: Any) -> None: ...
 
+# We subclass with "Any" because mocks are explicitly designed to stand in for other types,
+# something that can't be expressed with our static type system.
 class NonCallableMock(Base, Any):
     def __new__(
         cls: type[Self],